CVE-2023-53671

Boot hang via offline-CPU SRCU work queue

Published Oct 7, 2025 · Updated Oct 7, 2025

Denial of service in Linux Tree SRCU allows local users to hang a PowerPC kdump kernel during boot under a nonzero boot CPU. With SRCU_SIZE_SMALL, srcutree.c queues sdp->work unconditionally on CPU 0 even when that CPU is offline, so no worker executes it and __synchronize_srcu() never completes. Reachability requires a PowerPC kdump boot with maxcpus=1 and a nonzero boot CPU; the resulting kernel remains blocked rather than completing startup.

CVSS severity5.5
Medium
EPSS probability0.14%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Linux Tree SRCU allows local users to hang a PowerPC kdump kernel during boot under a nonzero boot CPU. With SRCU_SIZE_SMALL, srcutree.c queues sdp->work unconditionally on CPU 0 even when that CPU is offline, so no worker executes it and __synchronize_srcu() never completes. Reachability requires a PowerPC kdump boot with maxcpus=1 and a nonzero boot CPU; the resulting kernel remains blocked rather than completing startup.

The record

CVE
CVE-2023-53671
Published
Oct 7, 2025
Updated
Oct 7, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 7, 2025CVE publishedPublication date reported by the CVE source.
  2. Oct 7, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <2c4d26dad76eadaa45a24543e311e9ce5d09f04e
  2. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <7f24626d6dd844bfc6d1f492d214d29c86d02550
  3. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <c7c0bc03fa44942fe0fdc5ac52cda6e11529c0ea

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <2c4d26dad76eadaa45a24543e311e9ce5d09f04e; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <7f24626d6dd844bfc6d1f492d214d29c86d02550; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <c7c0bc03fa44942fe0fdc5ac52cda6e11529c0ea

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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